// If this is an integer, increment it by fourif (is_int($an_int)) {$an_int += 4;}

// If $a_bool is a string, print it out// (does not print out anything)if (is_string($a_bool)) { echo "String: $a_bool";}?>

To forcibly convert a variable to a certain type, either
cast the variable or use
the settype() function on it.

Note that a variable may be evaluated with different values in certain
situations, depending on what type it is at the time. For more information,
see the section on Type
Juggling. The type comparison
tables may also be useful, as they show examples of various
type-related comparisons.